Shrinkage behavior of low profile unsaturated polyester resins at low temperature and low pressure
- Ohio State Univ., Columbus, OH (United States)
In order to achieve excellent surface quality and dimension control of molded polymer composites, low profile additives (LPA) are widely used in low shrinkage unsaturated polyester (UPE) molding compound. Although the detailed LPA mechanism is still a subject of controversy, it is now generally agreed that the most important factor for the low profile behavior is the strong phase separation between LPA and UPE resin during curing. Among the extensive studies of LPA mechanism, most of the work focused on the reaction at high temperatures, since LPAs found most of their applications in high temperature and high pressure processes like sheet molding compound (SMC) and bulk molding compound (BMC). Recently, because of the growing interests of new processes such as low pressure SMC and vacuum infusion resin transfer molding, low shrinkage molding compound with the ability to be processed at low temperature and low pressure have attracted considerable attention from the composite industry. Therefore, further understanding of the low profile mechanism at low temperature and low pressure cure is necessary. Moreover, the relatively long reaction time at low temperature cure provides an opportunity to decouple the factors such as phase separation and microvoid formation, which occur almost at the same time in high temperature cure. The objective of this study is to determine LPA performance as well as to provide a better understanding of low profile mechanism at low temperature and low pressure.
- OSTI ID:
- 602965
- Report Number(s):
- CONF-961108--
- Country of Publication:
- United States
- Language:
- English
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